For some applications, it can be desirable to determine a temperature. Some of these applications involve operating a chip which implements electrical circuitry.
Various techniques of determining the temperature are known. A commonly applied technique relies on measuring a so-called Proportional To Absolute Temperature (PTAT) current in a resistor. The PTAT current is typically caused by a voltage difference between two diodes operated at different current densities. In particular, in such a technique an integrated design of a respective temperature sensor with a chip including further circuitry is possible (on-chip design).
However, such techniques face certain restrictions. E.g., the accuracy in determining the temperature which is achievable by measuring the PTAT current may be comparably limited. This may be due to a limited available area to implement the required circuitry. Further, typically a minimum voltage of, e.g., 1 Volt may be required for operation. Sometimes, providing the voltage may be difficult.
To achieve a better accuracy, sometimes external sensors are employed; then, the temperature sensor may not be according to the on-chip design. External sensors are not integrated with the chip. However, due to limitations in building space, employing external sensors is often not feasible. External sensors can also be comparably costly.